Project Summary Significance: Black drinkers experience more alcohol problems than White drinkers even at equivalent levels of alcohol use. These problems are pervasive, occurring across physical, social, and legal outcomes. The reasons that explain why Black drinkers are at elevated risk for experiencing alcohol problems are understudied and not well understood, but may involve differences in level of stress and acute response to alcohol. The proposed R01 examines these constructs both within the laboratory and in the natural environment using ecological momentary assessment (EMA) to identify proximal points of intervention for both Black and White drinkers. Aims: Aim 1 will examine racial differences in the anxiolytic effects of alcohol prior to and after a stress induction in the lab. Aim 2 will directly test if differential alcohol response measured in the lab strengthens the association between stress and alcohol cognitions (craving for alcohol, drinking motives), and accounts for racial differences in these cognitions. Aim 3 will examine the extent to which lab-based alcohol response and daily reports of stress explain racial differences in alcohol problems through 12-month follow-up. Hypotheses: We hypothesize that Black drinkers will have increased sensitivity to the anxiolytic effects of alcohol compared to White drinkers and that this sensitivity to alcohol as well as elevated stress will predict increased risky alcohol cognitions in EMA. Additionally, the association between stress and alcohol cognitions will be stronger for participants with the most sensitivity to the anxiolytic effects of alcohol. EMA alcohol cognitions will partially account for the association between alcohol response, stress, and alcohol problems during the EMA period and at the 6- and 12- month follow-ups. These processes and their transaction will partially account for why Black drinkers, relative to White drinkers, experience more alcohol problems. Approach: Young adult drinkers (N = 280; 21-30 years of age; 50% Black, 50% female) will be recruited from the community. Participants will first complete a semi-structured diagnostic interview and questionnaires and will then complete two laboratory sessions (placebo and alcohol; randomized order) with a standardized stress task to assess acute alcohol response. Next, participants will complete a 17-day EMA protocol to record fluctuations in stress, alcohol cognitions, alcohol response, alcohol use/problems. To allow for the prediction of prospective outcomes follow-up assessments at 6- and 12- months will be conducted and will include past 6 month self-reported alcohol use, alcohol problems, stress, and alcohol cognitions, as well as a 90-day timeline follow-back interview. This R01 proposal is directly in line with the NIAAA's strategic priorities to understand the role of stress in relation to alcohol problems and to decrease health disparities. The proposed research takes a critical step towards increasing our understanding of why Black drinkers are at greater risk for alcohol problems and will ultimately inform intervention efforts that are tailored to this under-studied, at-risk, population.